For heat exchange systems such as air conditioning systems, there are techniques for cooling a secondary object to be cooled (for example, an inverter in the heat exchange system) by using the refrigerant flowing in the refrigerant passage in the heat exchange system.
For example, the heat exchange system of Patent Document 1 provides a cooling element for cooling a secondary object to be cooled, with capillary tubes placed to precede and follow the cooling element so as to adjust the temperature (intermediate temperature) of the refrigerant passing through the cooling element.
However, in such a system, the two capillary tubes preceding and following the cooling element are fixed throttles, and it is therefore difficult to adjust the temperature of the cooling element when the operating conditions of the system or the conditions of air vary. Accordingly, condensation may occur in the cooling element.
On the other hand, in the heat exchange system of Patent Document 2, two electronic expansion valves are provided in series between a condenser and an evaporator, and a cooling element is provided between the two electronic expansion valves. The electronic expansion valves are variable throttles, and so the pressure difference occurring across both ends of the cooling element can be relatively freely adjusted by adjusting the valve lifts of the two electronic expansion valves. It is therefore possible to favorably adjust the temperature of the refrigerant flowing between the two electronic expansion valves, making it possible to cool the secondary cooled object without causing condensation.
Patent Document 1: Japanese Patent Application Laid-Open No. 62-69066 (1987)
Patent Document 2: Japanese Patent Application Laid-Open No. 11-23081 (1999)